U.S. patent number 4,798,532 [Application Number 07/113,400] was granted by the patent office on 1989-01-17 for flash smelting furnace.
This patent grant is currently assigned to Sumitomo Metal Mining Company Limited. Invention is credited to Takayoshi Kimura, Yoshiaki Mori, Yasuo Ojima.
United States Patent |
4,798,532 |
Kimura , et al. |
January 17, 1989 |
Flash smelting furnace
Abstract
A flash smelting furnace which comprises a reaction shaft, a
concentrate combustion device disposed at the top of the furnace
shaft, a settler disposed with one end thereof connected to the
lower part of the reaction shaft, an uptake disposed as connected
to the other end of the settler and at least one lance pipe
extending through the ceiling of the settler between the reaction
shaft and the uptake and adapted to blow at least powdery raw
materials and a reaction gas into the melt inside the settler.
Inventors: |
Kimura; Takayoshi (Niihama,
JP), Ojima; Yasuo (Niihama, JP), Mori;
Yoshiaki (Niihama, JP) |
Assignee: |
Sumitomo Metal Mining Company
Limited (Tokyo, JP)
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Family
ID: |
16374430 |
Appl.
No.: |
07/113,400 |
Filed: |
October 26, 1987 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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900698 |
Aug 27, 1986 |
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Foreign Application Priority Data
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Sep 5, 1985 [JP] |
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60-197433 |
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Current U.S.
Class: |
432/210; 110/238;
266/212; 266/227 |
Current CPC
Class: |
C22B
5/14 (20130101); C22B 15/0047 (20130101); C22B
23/025 (20130101); F27B 3/04 (20130101); F27B
3/045 (20130101); F27B 19/02 (20130101); F27D
3/18 (20130101) |
Current International
Class: |
C22B
5/14 (20060101); C22B 5/00 (20060101); C22B
23/02 (20060101); C22B 23/00 (20060101); C22B
15/00 (20060101); F27B 19/02 (20060101); F27B
3/00 (20060101); F27B 19/00 (20060101); F27B
3/04 (20060101); F27D 3/00 (20060101); F27D
3/18 (20060101); F26B 003/00 (); F27B 019/02 () |
Field of
Search: |
;432/161,197,210
;110/238 ;266/205,212,227,232,242 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Yuen; Henry C.
Attorney, Agent or Firm: Watson, Cole, Grindle &
Watson
Parent Case Text
This application is a continuation of application Ser. No. 900,698,
filed Aug. 27, 1986, now abandoned.
Claims
What is claimed is:
1. In a flash smelting furnace for producing matte from a copper or
nickel sulfide ore comprising a reaction shaft, a concentrate
combustion device disposed at a top of said reaction shaft, means
for supplying oxidizing gas to said top of said reaction shaft,
means for supplying powdered copper or nickel sulfide ore
concentrate to said top of said reaction shaft, a settler for
containing melt formed in said reaction shaft and having opposite
first and second ends and a ceiling, said first end of said settler
being connected to a lower part of said reaction shaft, and an
uptake connected to said second end of said settler, the
improvement wherein said flash smelting surface includes at least
one consumable lance pipe extending downwardly through the ceiling
of said settler between said furnace shaft and said uptake, means
for supplying powdery raw material which includes copper or nickel
sulfide ore concentrate to each of said lance pipes for discharge
against said melt in said settler, means for simultaneously
supplying a reaction gas to each of said lance pipes for discharge
against said melt in said settler, and means connected to each of
said lance pipes to move the associated lance pipe downwardly into
said settler as a lower end thereof in said settler is
consumed.
2. A flash smelting furnace according to claim 1, including means
for simultaneously supplying an auxiliary fuel to each of said
lance pipes for discharge against said melt in said settler.
Description
BACKGROUND OF THE INVENTION
1. FIELD OF THE INVENTION
This invention relates to improvements in and concerning a flash
smelting furnace for producing matte from a copper or nickel
sulfide ore as a smelting intermediate for the corresponding
metal.
2. DESCRIPTION OF THE PRIOR ART
The flash smelting furnace which uses a sulfide concentrate as a
raw material and which is popularly called a "flash furnace"
possesses many advantages as compared with the other smelting
furnaces and, on the other hand, suffers from many disadvantages.
By way of illustrating, the conventional flash furnace for copper
will be described with reference to FIG. 2.
In a flash furnace 1, a powdered concentrate 2 and preheated air 3
are jointly blown into a reaction shaft 5 of the furnace through a
concentrate burner 4 at the top of the furnace. Inside the furnace
shaft 5, sulfur and iron, which are combustible components of the
powdered concentrate 2, react with the hot air 3 and melt
themselves. The resulting melt is stored in a settler 6. In the
settler 6 which is a reservoir for the melt, the melt is divided by
differences in specific gravity into a matte 7, which is a mixture
of Cu.sub.2 S and FeS, and a slag 8, consisting mainly of
2FeO.SiO.sub.2. The slag 8 is discharged through a slag discharge
outlet 9 and introduced into an electric slag melting furnace 10.
In the meantime, the matte 7 is withdrawn via a matte discharge
outlet 11 in compliance with the demand from a converter which
constitutes itself a next step of operation.
Meanwhile, a hot waste gas 12 from the reaction shaft 5 is advanced
through the settler 6 and a uptake 13 and cooled in a boiler 14.
The slag 8 which has entered the electric slag cleaning furnace 10
is kept heated with the heat generated by the electricity fed in
through electrodes 15 and, when necessary, mixed as with lumps of
ore introduced into the electric slag cleaning furnace 10, with the
result that the copper component is further sedimented to the
furnace bottom and only the residual slag containing a copper
component is discharged via an outlet 16.
The conventional flash smelting furnace has entailed many drawbacks
as indicated below.
(1) Since the auxiliary fuel is used inside the reaction shaft 5 to
make up for insufficient calorific supply, an atmosphere of fairly
high temperature is formed inside the reaction shaft 5 by the heat
of reaction of the concentrate as the raw material and the heat of
combustion of the auxiliary fuel. An attempt at increasing the
amount of the concentrate to be treated results in a severe wearing
of the lining refractory bricks of the reaction shaft 5 by melting,
making it necessary to limit the amount of the concentrate to be
forwarded through the concentrate burner 4 and treated per unit
time to an extent at which the wearance of the bricks by smelting
is tolerable. This wearance of the bricks by smelting closely bears
on the thermal load of the reaction shaft. The loss is
conspicuously heavy when the thermal load exceeds 350,000
Kcal/m.sup.3.hr. Thus, the thermal load is desired to be not more
than 250,000 Kcal/m.sup.3.hr.
An addition to the amount of treatment can be realized by
increasing the inside diameter and height of the reaction shaft.
Since the reaction shaft consequently has an increased surface
area, the heat radiatd is increased and the amount of the auxiliary
fuel used in making up for the loss of heat is also increased. Such
an addition exclusively to the reaction shaft as described above
inevitably exposes the existing flash furnace to considerable
difficulties.
As a means of permitting treatment of an increased amount of the
concentrate, a method which resorts to an increase in the oxygen
content of the preheated air 3 or to an increase in the degree of
oxygen enrichment may be conceived. Again in this case, the
interior of the reaction shaft 5 suffers formation of an atmosphere
of still higher temperature. For the sake of avoiding loss of the
lining refractory bricks by melting, the amount of the concentrat
to be treated has its own upper limit.
(2) In the concentrate burner 4, the powdery concentrate 2 and the
preheated air 3 are blown into the empty space of the reaction
shaft 5 and the melt consequently formed falls in drops and
separates into the matte and the slag in the settler 6. The waste
gas 12 from the flash furnace 1, therefore, contains a large amount
of dust. This dust accumulates in the uptake 13, in the part
interconnecting the uptake 13 and the boiler 14, and inside the
boiler 14 and offers obstacle to the passage of gas.
Since the dust contains valuable metals, it is recovered as in the
boiler and the electric static precipitator and returned to the
flash furnace 1 as entrained by the concentrate 2 being fed
thereto. When the recovered dust which has undergone further
oxidation and has been deprived of combustibility is to treated in
the concentrate burner 4, the amount of the auxiliary fuel required
is increased and the incombustible dust has a high melting point.
Thus, the proportion in which the dust is entrained by the waste
gas and taken out of the furnace is increased to add to the amount
of dust.
(3) An attempt at increasing the amount of the concentrate to be
treated in the concentrate burner 4 results in a deviation from the
optimum gas flow rate inside the reaction shaft 5. Consequently,
the ratio of dust generation described in (2) above is increased.
Thus, for the sake of curbing the ratio of dust generation, the
amount of the concentrate forwarded through the concentrate burner
for treatment has its own upper limit.
(4) The reaction shaft 5 is filled with an oxidative atmosphere.
Particularly the low-temperature zone in which the powdery raw
material blown in through the concentrate burner 4 has not yet been
heated sufficiently to the prescribed level is liable to form
magnetite. The magnetite offers various hindrances to the furnace
operation. For example, the magnetite increases the viscosity of
the slag, impairs the separation of the slag from the matte and
brings about an increase in the copper content of the slag.
Besides, since the magnetite has a high density, it settles to and
accumulates on the hearth, raises the surface of the hearth, and
decreases the available volume of the hearth. Further, the
magnetite combines itself with other oxide, particulary Cr.sub.2
O.sub.3, and gives rise to a slag of high viscosity as an
intermediate layer between the matte and the slag and interferes
with the separation of the matte from the slag. The slag of high
viscosity mentioned above possesses a high melting point and a high
viscidity and, consequently renders the discharge of the slag
through the slag outlet 9 difficult.
SUMMARY OF THE INVENTION
For the solution of the drawbacks suffered by the conventional
flash furnace as described above, this invention aims to provide a
flash smelting furnace which is capable of increasing the amount of
the concentrate to be treated without requiring any increase of
size beyond the size of the existing flash smelting furnace.
The other functions and characteristic features of this invention
will become apparent from the further disclosure of the invention
to be given hereinbelow with reference to the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an explanatory diagram of a typical flash smelting
furnace embodying the present invention, and
FIG. 1A and FIG. 1B are magnified diagrams of the leading end of a
lance pipe shown in FIG. 1.
FIG. 2 is an explanatory diagram of the conventional flash smelting
furnace.
DETAILED DESCRIPTION OF THE INVENTION
To accomplish the object described above, this invention provides a
flash smelting furnace comprising a reaction shaft, a concentrate
combustion device disposed at the top of the reaction shaft, a
settler disposed with one end thereof connected to the lower part
of the furnace shaft, and a uptake disposed as connected to the
other end of the settler, which flash smelting furnace is
characterized by being provided with at least one lance pipe laid
through the ceiling of the settler between the furnace shaft and
the uptake and adapted to blow at least powdery raw materials and a
reaction gas into the melt inside the settler.
One working example of this invention will be described below with
reference to FIG. 1. As illustrated in FIG. 1, the flash smelting
furnace of this invention is identical with the conventional
countertype in respect that it is provided with a reaction shaft 5
incorporating therein a concentrate burner 4, a settler 6, and a
uptake 13. The settler 6 is provided in the ceiling thereof with a
through hole 17 for permitting insertion of a lance pipe. Through
this hole 17, a top lance pipe 18 is inserted in such a manner that
it will blow the powdery raw material 19 and the gas 20 for
reaction and optionally the auxiliary fuel 21 into the melt of the
slag 8 or the matte 7 collected inside the settler 6. The number of
lance pipes 18 so used may be one or two or more, depending on the
amount of the powdery raw material to be supplied through the
settler 6. The lance pipe 18 is of a consumable type such that it
will be gradually lowered by device 30 as the leading (lower) end
thereof is worn out and will eventually be succeeded by a fresh
supply. The lance pipe 18 may be otherwise of a non-consumable type
such that it will be fixed above the slag 8 to position the leading
end of the lance pipe apart from the slag level by 400-500 mm.
In accordance with the flash smelting furnace of this invention,
the powdery concentrate 2 supplied to the reaction shaft 5 is
melted by the reaction with the gas 3 and the resulting melt is
separated by differences in specific gravity into the slag 8 and
the matte 7 in the settler 6. The waste gas which arises in the
reaction shaft 5 is forwarded through the empty space of the
settler 6 and the uptake 13 to the boiler 14.
In the meantime, the top lance pipe 18 inserted through the hole 17
in the ceiling of the settler 6 permits powdery raw materials 19
such as concentrate, recycled dust, copper bearing material, and
flux, a reaction gas 20 such as air or oxygen enriched air, and
optionally an auxiliary fuel 21 such as heavy oil or carbon dust
coal, coke to be blown into the melt held inside the settler 6. The
leading end of the lance pipe 18 is slightly immersed below the
surface of the melt so that the forced flow of the powdery raw
materials 19, the reaction gas 20, etc., will form a depressed
surface on the surface of the melt (as illustrated in FIG. 1A). If
the powdery raw materials and reaction gas are blown at a high
velocity, the leading end of the lance pipe may be kept apart from
the surface of the melt, as shown in FIG. 1B.
The powdery raw materials thus blown in through the leading end of
the lance pipe immediately find their way into the melt, react with
the melt and dissolve. The waste gas generated herein is discharged
through the uptake in conjunction with the waste gas generated in
the reaction shaft 5.
The flash smelting furnace of this invention acquires a notably
large capacity for smelting the concentrate as compared with the
conventional flash furnace because it enables the same amount of
concentrate to be forwarded through the concentrate burner and
melted in the furnace shaft as in the conventional flash smelting
furnace and further enables an additional amount of concentrate to
be introduced through the lance pipe and melted. In this case, the
form of the reaction which the ore undergoes inside the reaction
shaft is not affected by the lance pipe to be used in the settler.
The reaction is allowed to proceed under the optimum
conditions.
When the waste gas arising in the reaction shaft and containing
large amount of dust passes through the empty space inside the
settler, it advances across the splash of the melt caused by the
forced flow introduced through the lance pipe. Since part of the
dust is mechanically caught by the drops of the melt, and the dust
content of waste gas emanating from the uptake is proportionately
decreased and the dust trouble caused in the uptake, the boiler,
and the part interconnecting them is alleviated. Until the
magnetite formed by the reaction of the concentrate fed in through
the reaction shaft is discharged via the slag hole, the slag
containing the phase of slag of large viscosity is vigorously
stirred by the concentrate and the reaction gas which are blown in
via the lance pipe. Since the magnetite in the slag of large
viscosity is not present in equilibrium therein, the greater part
of the magnetite is reduced by the fact that the slag is
homogenized by the stirring. Besides, the magnetite is further
reduced by the reaction:
which is caused by the FeS in the concentrate blown in through the
lance pipe. As the result, the loss of copper into the slag is
decreased and the difficulty in the discharge of the slag through
the slag outlet due to the high viscosity is eliminated.
This invention eliminates the drawbacks suffered by the
conventional flash smelting furnace as described above and brings
about the following advantages as well.
(1) Since the non-combustible raw materials such as repeat dust
which have heretofore been treated through the concentrate burner
can be blown in via the lance pipe into the melt, the solubility of
the non-combustible raw materials is improved and the ratio of dust
generation is lowered and the ratio of consumption of the auxiliary
fuel in the concentrate burner is lowered.
(2) The amount of the concentrate advanced for treatment through
the concentrate burner can be lowered by introducing additional
concentrate via the lance pipe. The volatility of the volatile
impurities can be improved because the reaction inside the reaction
shaft can be carried out at a temperature higher than in the
conventional furnace by using air of higher oxygen content. Thus,
the flash smelting furnace of this invention is enabled to treat a
concentrate of a higher content of impurities than tolerable in the
conventional furnace. Further, the efficiency of the removal of
volatile impurities can be expected to be enhanced by feeding a
concentrate of a high content of volatile impurities through the
concentrate burner and a concentrate of a low content of volatile
impurities via the lance pipe.
(3) The copper content in the slag to be discharged through the
slag outlet can be further lowered even to the extent of permitting
omission of the slag cleaning furnace by blowing a reducing agent
via the lance pipe as occasion demands.
While the present invention has been described by means of a
specific embodiment, it is to be understood that numerous changes
and modifications may be made therein without departing from the
spirit and scope of the invention defined in the appended
claims.
* * * * *